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annotate CSP2/CSP2_env/env-d9b9114564458d9d-741b3de822f2aaca6c6caa4325c4afce/lib/python3.8/site-packages/pytz/tzinfo.py @ 69:33d812a61356

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planemo upload commit 2e9511a184a1ca667c7be0c6321a36dc4e3d116d
author jpayne
date Tue, 18 Mar 2025 17:55:14 -0400
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jpayne@69 1 '''Base classes and helpers for building zone specific tzinfo classes'''
jpayne@69 2
jpayne@69 3 from datetime import datetime, timedelta, tzinfo
jpayne@69 4 from bisect import bisect_right
jpayne@69 5 try:
jpayne@69 6 set
jpayne@69 7 except NameError:
jpayne@69 8 from sets import Set as set
jpayne@69 9
jpayne@69 10 import pytz
jpayne@69 11 from pytz.exceptions import AmbiguousTimeError, NonExistentTimeError
jpayne@69 12
jpayne@69 13 __all__ = []
jpayne@69 14
jpayne@69 15 _timedelta_cache = {}
jpayne@69 16
jpayne@69 17
jpayne@69 18 def memorized_timedelta(seconds):
jpayne@69 19 '''Create only one instance of each distinct timedelta'''
jpayne@69 20 try:
jpayne@69 21 return _timedelta_cache[seconds]
jpayne@69 22 except KeyError:
jpayne@69 23 delta = timedelta(seconds=seconds)
jpayne@69 24 _timedelta_cache[seconds] = delta
jpayne@69 25 return delta
jpayne@69 26
jpayne@69 27
jpayne@69 28 _epoch = datetime(1970, 1, 1, 0, 0) # datetime.utcfromtimestamp(0)
jpayne@69 29 _datetime_cache = {0: _epoch}
jpayne@69 30
jpayne@69 31
jpayne@69 32 def memorized_datetime(seconds):
jpayne@69 33 '''Create only one instance of each distinct datetime'''
jpayne@69 34 try:
jpayne@69 35 return _datetime_cache[seconds]
jpayne@69 36 except KeyError:
jpayne@69 37 # NB. We can't just do datetime.fromtimestamp(seconds, tz=timezone.utc).replace(tzinfo=None)
jpayne@69 38 # as this fails with negative values under Windows (Bug #90096)
jpayne@69 39 dt = _epoch + timedelta(seconds=seconds)
jpayne@69 40 _datetime_cache[seconds] = dt
jpayne@69 41 return dt
jpayne@69 42
jpayne@69 43
jpayne@69 44 _ttinfo_cache = {}
jpayne@69 45
jpayne@69 46
jpayne@69 47 def memorized_ttinfo(*args):
jpayne@69 48 '''Create only one instance of each distinct tuple'''
jpayne@69 49 try:
jpayne@69 50 return _ttinfo_cache[args]
jpayne@69 51 except KeyError:
jpayne@69 52 ttinfo = (
jpayne@69 53 memorized_timedelta(args[0]),
jpayne@69 54 memorized_timedelta(args[1]),
jpayne@69 55 args[2]
jpayne@69 56 )
jpayne@69 57 _ttinfo_cache[args] = ttinfo
jpayne@69 58 return ttinfo
jpayne@69 59
jpayne@69 60
jpayne@69 61 _notime = memorized_timedelta(0)
jpayne@69 62
jpayne@69 63
jpayne@69 64 def _to_seconds(td):
jpayne@69 65 '''Convert a timedelta to seconds'''
jpayne@69 66 return td.seconds + td.days * 24 * 60 * 60
jpayne@69 67
jpayne@69 68
jpayne@69 69 class BaseTzInfo(tzinfo):
jpayne@69 70 # Overridden in subclass
jpayne@69 71 _utcoffset = None
jpayne@69 72 _tzname = None
jpayne@69 73 zone = None
jpayne@69 74
jpayne@69 75 def __str__(self):
jpayne@69 76 return self.zone
jpayne@69 77
jpayne@69 78
jpayne@69 79 class StaticTzInfo(BaseTzInfo):
jpayne@69 80 '''A timezone that has a constant offset from UTC
jpayne@69 81
jpayne@69 82 These timezones are rare, as most locations have changed their
jpayne@69 83 offset at some point in their history
jpayne@69 84 '''
jpayne@69 85 def fromutc(self, dt):
jpayne@69 86 '''See datetime.tzinfo.fromutc'''
jpayne@69 87 if dt.tzinfo is not None and dt.tzinfo is not self:
jpayne@69 88 raise ValueError('fromutc: dt.tzinfo is not self')
jpayne@69 89 return (dt + self._utcoffset).replace(tzinfo=self)
jpayne@69 90
jpayne@69 91 def utcoffset(self, dt, is_dst=None):
jpayne@69 92 '''See datetime.tzinfo.utcoffset
jpayne@69 93
jpayne@69 94 is_dst is ignored for StaticTzInfo, and exists only to
jpayne@69 95 retain compatibility with DstTzInfo.
jpayne@69 96 '''
jpayne@69 97 return self._utcoffset
jpayne@69 98
jpayne@69 99 def dst(self, dt, is_dst=None):
jpayne@69 100 '''See datetime.tzinfo.dst
jpayne@69 101
jpayne@69 102 is_dst is ignored for StaticTzInfo, and exists only to
jpayne@69 103 retain compatibility with DstTzInfo.
jpayne@69 104 '''
jpayne@69 105 return _notime
jpayne@69 106
jpayne@69 107 def tzname(self, dt, is_dst=None):
jpayne@69 108 '''See datetime.tzinfo.tzname
jpayne@69 109
jpayne@69 110 is_dst is ignored for StaticTzInfo, and exists only to
jpayne@69 111 retain compatibility with DstTzInfo.
jpayne@69 112 '''
jpayne@69 113 return self._tzname
jpayne@69 114
jpayne@69 115 def localize(self, dt, is_dst=False):
jpayne@69 116 '''Convert naive time to local time'''
jpayne@69 117 if dt.tzinfo is not None:
jpayne@69 118 raise ValueError('Not naive datetime (tzinfo is already set)')
jpayne@69 119 return dt.replace(tzinfo=self)
jpayne@69 120
jpayne@69 121 def normalize(self, dt, is_dst=False):
jpayne@69 122 '''Correct the timezone information on the given datetime.
jpayne@69 123
jpayne@69 124 This is normally a no-op, as StaticTzInfo timezones never have
jpayne@69 125 ambiguous cases to correct:
jpayne@69 126
jpayne@69 127 >>> from pytz import timezone
jpayne@69 128 >>> gmt = timezone('GMT')
jpayne@69 129 >>> isinstance(gmt, StaticTzInfo)
jpayne@69 130 True
jpayne@69 131 >>> dt = datetime(2011, 5, 8, 1, 2, 3, tzinfo=gmt)
jpayne@69 132 >>> gmt.normalize(dt) is dt
jpayne@69 133 True
jpayne@69 134
jpayne@69 135 The supported method of converting between timezones is to use
jpayne@69 136 datetime.astimezone(). Currently normalize() also works:
jpayne@69 137
jpayne@69 138 >>> la = timezone('America/Los_Angeles')
jpayne@69 139 >>> dt = la.localize(datetime(2011, 5, 7, 1, 2, 3))
jpayne@69 140 >>> fmt = '%Y-%m-%d %H:%M:%S %Z (%z)'
jpayne@69 141 >>> gmt.normalize(dt).strftime(fmt)
jpayne@69 142 '2011-05-07 08:02:03 GMT (+0000)'
jpayne@69 143 '''
jpayne@69 144 if dt.tzinfo is self:
jpayne@69 145 return dt
jpayne@69 146 if dt.tzinfo is None:
jpayne@69 147 raise ValueError('Naive time - no tzinfo set')
jpayne@69 148 return dt.astimezone(self)
jpayne@69 149
jpayne@69 150 def __repr__(self):
jpayne@69 151 return '<StaticTzInfo %r>' % (self.zone,)
jpayne@69 152
jpayne@69 153 def __reduce__(self):
jpayne@69 154 # Special pickle to zone remains a singleton and to cope with
jpayne@69 155 # database changes.
jpayne@69 156 return pytz._p, (self.zone,)
jpayne@69 157
jpayne@69 158
jpayne@69 159 class DstTzInfo(BaseTzInfo):
jpayne@69 160 '''A timezone that has a variable offset from UTC
jpayne@69 161
jpayne@69 162 The offset might change if daylight saving time comes into effect,
jpayne@69 163 or at a point in history when the region decides to change their
jpayne@69 164 timezone definition.
jpayne@69 165 '''
jpayne@69 166 # Overridden in subclass
jpayne@69 167
jpayne@69 168 # Sorted list of DST transition times, UTC
jpayne@69 169 _utc_transition_times = None
jpayne@69 170
jpayne@69 171 # [(utcoffset, dstoffset, tzname)] corresponding to
jpayne@69 172 # _utc_transition_times entries
jpayne@69 173 _transition_info = None
jpayne@69 174
jpayne@69 175 zone = None
jpayne@69 176
jpayne@69 177 # Set in __init__
jpayne@69 178
jpayne@69 179 _tzinfos = None
jpayne@69 180 _dst = None # DST offset
jpayne@69 181
jpayne@69 182 def __init__(self, _inf=None, _tzinfos=None):
jpayne@69 183 if _inf:
jpayne@69 184 self._tzinfos = _tzinfos
jpayne@69 185 self._utcoffset, self._dst, self._tzname = _inf
jpayne@69 186 else:
jpayne@69 187 _tzinfos = {}
jpayne@69 188 self._tzinfos = _tzinfos
jpayne@69 189 self._utcoffset, self._dst, self._tzname = (
jpayne@69 190 self._transition_info[0])
jpayne@69 191 _tzinfos[self._transition_info[0]] = self
jpayne@69 192 for inf in self._transition_info[1:]:
jpayne@69 193 if inf not in _tzinfos:
jpayne@69 194 _tzinfos[inf] = self.__class__(inf, _tzinfos)
jpayne@69 195
jpayne@69 196 def fromutc(self, dt):
jpayne@69 197 '''See datetime.tzinfo.fromutc'''
jpayne@69 198 if (dt.tzinfo is not None and
jpayne@69 199 getattr(dt.tzinfo, '_tzinfos', None) is not self._tzinfos):
jpayne@69 200 raise ValueError('fromutc: dt.tzinfo is not self')
jpayne@69 201 dt = dt.replace(tzinfo=None)
jpayne@69 202 idx = max(0, bisect_right(self._utc_transition_times, dt) - 1)
jpayne@69 203 inf = self._transition_info[idx]
jpayne@69 204 return (dt + inf[0]).replace(tzinfo=self._tzinfos[inf])
jpayne@69 205
jpayne@69 206 def normalize(self, dt):
jpayne@69 207 '''Correct the timezone information on the given datetime
jpayne@69 208
jpayne@69 209 If date arithmetic crosses DST boundaries, the tzinfo
jpayne@69 210 is not magically adjusted. This method normalizes the
jpayne@69 211 tzinfo to the correct one.
jpayne@69 212
jpayne@69 213 To test, first we need to do some setup
jpayne@69 214
jpayne@69 215 >>> from pytz import timezone
jpayne@69 216 >>> utc = timezone('UTC')
jpayne@69 217 >>> eastern = timezone('US/Eastern')
jpayne@69 218 >>> fmt = '%Y-%m-%d %H:%M:%S %Z (%z)'
jpayne@69 219
jpayne@69 220 We next create a datetime right on an end-of-DST transition point,
jpayne@69 221 the instant when the wallclocks are wound back one hour.
jpayne@69 222
jpayne@69 223 >>> utc_dt = datetime(2002, 10, 27, 6, 0, 0, tzinfo=utc)
jpayne@69 224 >>> loc_dt = utc_dt.astimezone(eastern)
jpayne@69 225 >>> loc_dt.strftime(fmt)
jpayne@69 226 '2002-10-27 01:00:00 EST (-0500)'
jpayne@69 227
jpayne@69 228 Now, if we subtract a few minutes from it, note that the timezone
jpayne@69 229 information has not changed.
jpayne@69 230
jpayne@69 231 >>> before = loc_dt - timedelta(minutes=10)
jpayne@69 232 >>> before.strftime(fmt)
jpayne@69 233 '2002-10-27 00:50:00 EST (-0500)'
jpayne@69 234
jpayne@69 235 But we can fix that by calling the normalize method
jpayne@69 236
jpayne@69 237 >>> before = eastern.normalize(before)
jpayne@69 238 >>> before.strftime(fmt)
jpayne@69 239 '2002-10-27 01:50:00 EDT (-0400)'
jpayne@69 240
jpayne@69 241 The supported method of converting between timezones is to use
jpayne@69 242 datetime.astimezone(). Currently, normalize() also works:
jpayne@69 243
jpayne@69 244 >>> th = timezone('Asia/Bangkok')
jpayne@69 245 >>> am = timezone('Europe/Amsterdam')
jpayne@69 246 >>> dt = th.localize(datetime(2011, 5, 7, 1, 2, 3))
jpayne@69 247 >>> fmt = '%Y-%m-%d %H:%M:%S %Z (%z)'
jpayne@69 248 >>> am.normalize(dt).strftime(fmt)
jpayne@69 249 '2011-05-06 20:02:03 CEST (+0200)'
jpayne@69 250 '''
jpayne@69 251 if dt.tzinfo is None:
jpayne@69 252 raise ValueError('Naive time - no tzinfo set')
jpayne@69 253
jpayne@69 254 # Convert dt in localtime to UTC
jpayne@69 255 offset = dt.tzinfo._utcoffset
jpayne@69 256 dt = dt.replace(tzinfo=None)
jpayne@69 257 dt = dt - offset
jpayne@69 258 # convert it back, and return it
jpayne@69 259 return self.fromutc(dt)
jpayne@69 260
jpayne@69 261 def localize(self, dt, is_dst=False):
jpayne@69 262 '''Convert naive time to local time.
jpayne@69 263
jpayne@69 264 This method should be used to construct localtimes, rather
jpayne@69 265 than passing a tzinfo argument to a datetime constructor.
jpayne@69 266
jpayne@69 267 is_dst is used to determine the correct timezone in the ambigous
jpayne@69 268 period at the end of daylight saving time.
jpayne@69 269
jpayne@69 270 >>> from pytz import timezone
jpayne@69 271 >>> fmt = '%Y-%m-%d %H:%M:%S %Z (%z)'
jpayne@69 272 >>> amdam = timezone('Europe/Amsterdam')
jpayne@69 273 >>> dt = datetime(2004, 10, 31, 2, 0, 0)
jpayne@69 274 >>> loc_dt1 = amdam.localize(dt, is_dst=True)
jpayne@69 275 >>> loc_dt2 = amdam.localize(dt, is_dst=False)
jpayne@69 276 >>> loc_dt1.strftime(fmt)
jpayne@69 277 '2004-10-31 02:00:00 CEST (+0200)'
jpayne@69 278 >>> loc_dt2.strftime(fmt)
jpayne@69 279 '2004-10-31 02:00:00 CET (+0100)'
jpayne@69 280 >>> str(loc_dt2 - loc_dt1)
jpayne@69 281 '1:00:00'
jpayne@69 282
jpayne@69 283 Use is_dst=None to raise an AmbiguousTimeError for ambiguous
jpayne@69 284 times at the end of daylight saving time
jpayne@69 285
jpayne@69 286 >>> try:
jpayne@69 287 ... loc_dt1 = amdam.localize(dt, is_dst=None)
jpayne@69 288 ... except AmbiguousTimeError:
jpayne@69 289 ... print('Ambiguous')
jpayne@69 290 Ambiguous
jpayne@69 291
jpayne@69 292 is_dst defaults to False
jpayne@69 293
jpayne@69 294 >>> amdam.localize(dt) == amdam.localize(dt, False)
jpayne@69 295 True
jpayne@69 296
jpayne@69 297 is_dst is also used to determine the correct timezone in the
jpayne@69 298 wallclock times jumped over at the start of daylight saving time.
jpayne@69 299
jpayne@69 300 >>> pacific = timezone('US/Pacific')
jpayne@69 301 >>> dt = datetime(2008, 3, 9, 2, 0, 0)
jpayne@69 302 >>> ploc_dt1 = pacific.localize(dt, is_dst=True)
jpayne@69 303 >>> ploc_dt2 = pacific.localize(dt, is_dst=False)
jpayne@69 304 >>> ploc_dt1.strftime(fmt)
jpayne@69 305 '2008-03-09 02:00:00 PDT (-0700)'
jpayne@69 306 >>> ploc_dt2.strftime(fmt)
jpayne@69 307 '2008-03-09 02:00:00 PST (-0800)'
jpayne@69 308 >>> str(ploc_dt2 - ploc_dt1)
jpayne@69 309 '1:00:00'
jpayne@69 310
jpayne@69 311 Use is_dst=None to raise a NonExistentTimeError for these skipped
jpayne@69 312 times.
jpayne@69 313
jpayne@69 314 >>> try:
jpayne@69 315 ... loc_dt1 = pacific.localize(dt, is_dst=None)
jpayne@69 316 ... except NonExistentTimeError:
jpayne@69 317 ... print('Non-existent')
jpayne@69 318 Non-existent
jpayne@69 319 '''
jpayne@69 320 if dt.tzinfo is not None:
jpayne@69 321 raise ValueError('Not naive datetime (tzinfo is already set)')
jpayne@69 322
jpayne@69 323 # Find the two best possibilities.
jpayne@69 324 possible_loc_dt = set()
jpayne@69 325 for delta in [timedelta(days=-1), timedelta(days=1)]:
jpayne@69 326 loc_dt = dt + delta
jpayne@69 327 idx = max(0, bisect_right(
jpayne@69 328 self._utc_transition_times, loc_dt) - 1)
jpayne@69 329 inf = self._transition_info[idx]
jpayne@69 330 tzinfo = self._tzinfos[inf]
jpayne@69 331 loc_dt = tzinfo.normalize(dt.replace(tzinfo=tzinfo))
jpayne@69 332 if loc_dt.replace(tzinfo=None) == dt:
jpayne@69 333 possible_loc_dt.add(loc_dt)
jpayne@69 334
jpayne@69 335 if len(possible_loc_dt) == 1:
jpayne@69 336 return possible_loc_dt.pop()
jpayne@69 337
jpayne@69 338 # If there are no possibly correct timezones, we are attempting
jpayne@69 339 # to convert a time that never happened - the time period jumped
jpayne@69 340 # during the start-of-DST transition period.
jpayne@69 341 if len(possible_loc_dt) == 0:
jpayne@69 342 # If we refuse to guess, raise an exception.
jpayne@69 343 if is_dst is None:
jpayne@69 344 raise NonExistentTimeError(dt)
jpayne@69 345
jpayne@69 346 # If we are forcing the pre-DST side of the DST transition, we
jpayne@69 347 # obtain the correct timezone by winding the clock forward a few
jpayne@69 348 # hours.
jpayne@69 349 elif is_dst:
jpayne@69 350 return self.localize(
jpayne@69 351 dt + timedelta(hours=6), is_dst=True) - timedelta(hours=6)
jpayne@69 352
jpayne@69 353 # If we are forcing the post-DST side of the DST transition, we
jpayne@69 354 # obtain the correct timezone by winding the clock back.
jpayne@69 355 else:
jpayne@69 356 return self.localize(
jpayne@69 357 dt - timedelta(hours=6),
jpayne@69 358 is_dst=False) + timedelta(hours=6)
jpayne@69 359
jpayne@69 360 # If we get this far, we have multiple possible timezones - this
jpayne@69 361 # is an ambiguous case occurring during the end-of-DST transition.
jpayne@69 362
jpayne@69 363 # If told to be strict, raise an exception since we have an
jpayne@69 364 # ambiguous case
jpayne@69 365 if is_dst is None:
jpayne@69 366 raise AmbiguousTimeError(dt)
jpayne@69 367
jpayne@69 368 # Filter out the possiblilities that don't match the requested
jpayne@69 369 # is_dst
jpayne@69 370 filtered_possible_loc_dt = [
jpayne@69 371 p for p in possible_loc_dt if bool(p.tzinfo._dst) == is_dst
jpayne@69 372 ]
jpayne@69 373
jpayne@69 374 # Hopefully we only have one possibility left. Return it.
jpayne@69 375 if len(filtered_possible_loc_dt) == 1:
jpayne@69 376 return filtered_possible_loc_dt[0]
jpayne@69 377
jpayne@69 378 if len(filtered_possible_loc_dt) == 0:
jpayne@69 379 filtered_possible_loc_dt = list(possible_loc_dt)
jpayne@69 380
jpayne@69 381 # If we get this far, we have in a wierd timezone transition
jpayne@69 382 # where the clocks have been wound back but is_dst is the same
jpayne@69 383 # in both (eg. Europe/Warsaw 1915 when they switched to CET).
jpayne@69 384 # At this point, we just have to guess unless we allow more
jpayne@69 385 # hints to be passed in (such as the UTC offset or abbreviation),
jpayne@69 386 # but that is just getting silly.
jpayne@69 387 #
jpayne@69 388 # Choose the earliest (by UTC) applicable timezone if is_dst=True
jpayne@69 389 # Choose the latest (by UTC) applicable timezone if is_dst=False
jpayne@69 390 # i.e., behave like end-of-DST transition
jpayne@69 391 dates = {} # utc -> local
jpayne@69 392 for local_dt in filtered_possible_loc_dt:
jpayne@69 393 utc_time = (
jpayne@69 394 local_dt.replace(tzinfo=None) - local_dt.tzinfo._utcoffset)
jpayne@69 395 assert utc_time not in dates
jpayne@69 396 dates[utc_time] = local_dt
jpayne@69 397 return dates[[min, max][not is_dst](dates)]
jpayne@69 398
jpayne@69 399 def utcoffset(self, dt, is_dst=None):
jpayne@69 400 '''See datetime.tzinfo.utcoffset
jpayne@69 401
jpayne@69 402 The is_dst parameter may be used to remove ambiguity during DST
jpayne@69 403 transitions.
jpayne@69 404
jpayne@69 405 >>> from pytz import timezone
jpayne@69 406 >>> tz = timezone('America/St_Johns')
jpayne@69 407 >>> ambiguous = datetime(2009, 10, 31, 23, 30)
jpayne@69 408
jpayne@69 409 >>> str(tz.utcoffset(ambiguous, is_dst=False))
jpayne@69 410 '-1 day, 20:30:00'
jpayne@69 411
jpayne@69 412 >>> str(tz.utcoffset(ambiguous, is_dst=True))
jpayne@69 413 '-1 day, 21:30:00'
jpayne@69 414
jpayne@69 415 >>> try:
jpayne@69 416 ... tz.utcoffset(ambiguous)
jpayne@69 417 ... except AmbiguousTimeError:
jpayne@69 418 ... print('Ambiguous')
jpayne@69 419 Ambiguous
jpayne@69 420
jpayne@69 421 '''
jpayne@69 422 if dt is None:
jpayne@69 423 return None
jpayne@69 424 elif dt.tzinfo is not self:
jpayne@69 425 dt = self.localize(dt, is_dst)
jpayne@69 426 return dt.tzinfo._utcoffset
jpayne@69 427 else:
jpayne@69 428 return self._utcoffset
jpayne@69 429
jpayne@69 430 def dst(self, dt, is_dst=None):
jpayne@69 431 '''See datetime.tzinfo.dst
jpayne@69 432
jpayne@69 433 The is_dst parameter may be used to remove ambiguity during DST
jpayne@69 434 transitions.
jpayne@69 435
jpayne@69 436 >>> from pytz import timezone
jpayne@69 437 >>> tz = timezone('America/St_Johns')
jpayne@69 438
jpayne@69 439 >>> normal = datetime(2009, 9, 1)
jpayne@69 440
jpayne@69 441 >>> str(tz.dst(normal))
jpayne@69 442 '1:00:00'
jpayne@69 443 >>> str(tz.dst(normal, is_dst=False))
jpayne@69 444 '1:00:00'
jpayne@69 445 >>> str(tz.dst(normal, is_dst=True))
jpayne@69 446 '1:00:00'
jpayne@69 447
jpayne@69 448 >>> ambiguous = datetime(2009, 10, 31, 23, 30)
jpayne@69 449
jpayne@69 450 >>> str(tz.dst(ambiguous, is_dst=False))
jpayne@69 451 '0:00:00'
jpayne@69 452 >>> str(tz.dst(ambiguous, is_dst=True))
jpayne@69 453 '1:00:00'
jpayne@69 454 >>> try:
jpayne@69 455 ... tz.dst(ambiguous)
jpayne@69 456 ... except AmbiguousTimeError:
jpayne@69 457 ... print('Ambiguous')
jpayne@69 458 Ambiguous
jpayne@69 459
jpayne@69 460 '''
jpayne@69 461 if dt is None:
jpayne@69 462 return None
jpayne@69 463 elif dt.tzinfo is not self:
jpayne@69 464 dt = self.localize(dt, is_dst)
jpayne@69 465 return dt.tzinfo._dst
jpayne@69 466 else:
jpayne@69 467 return self._dst
jpayne@69 468
jpayne@69 469 def tzname(self, dt, is_dst=None):
jpayne@69 470 '''See datetime.tzinfo.tzname
jpayne@69 471
jpayne@69 472 The is_dst parameter may be used to remove ambiguity during DST
jpayne@69 473 transitions.
jpayne@69 474
jpayne@69 475 >>> from pytz import timezone
jpayne@69 476 >>> tz = timezone('America/St_Johns')
jpayne@69 477
jpayne@69 478 >>> normal = datetime(2009, 9, 1)
jpayne@69 479
jpayne@69 480 >>> tz.tzname(normal)
jpayne@69 481 'NDT'
jpayne@69 482 >>> tz.tzname(normal, is_dst=False)
jpayne@69 483 'NDT'
jpayne@69 484 >>> tz.tzname(normal, is_dst=True)
jpayne@69 485 'NDT'
jpayne@69 486
jpayne@69 487 >>> ambiguous = datetime(2009, 10, 31, 23, 30)
jpayne@69 488
jpayne@69 489 >>> tz.tzname(ambiguous, is_dst=False)
jpayne@69 490 'NST'
jpayne@69 491 >>> tz.tzname(ambiguous, is_dst=True)
jpayne@69 492 'NDT'
jpayne@69 493 >>> try:
jpayne@69 494 ... tz.tzname(ambiguous)
jpayne@69 495 ... except AmbiguousTimeError:
jpayne@69 496 ... print('Ambiguous')
jpayne@69 497 Ambiguous
jpayne@69 498 '''
jpayne@69 499 if dt is None:
jpayne@69 500 return self.zone
jpayne@69 501 elif dt.tzinfo is not self:
jpayne@69 502 dt = self.localize(dt, is_dst)
jpayne@69 503 return dt.tzinfo._tzname
jpayne@69 504 else:
jpayne@69 505 return self._tzname
jpayne@69 506
jpayne@69 507 def __repr__(self):
jpayne@69 508 if self._dst:
jpayne@69 509 dst = 'DST'
jpayne@69 510 else:
jpayne@69 511 dst = 'STD'
jpayne@69 512 if self._utcoffset > _notime:
jpayne@69 513 return '<DstTzInfo %r %s+%s %s>' % (
jpayne@69 514 self.zone, self._tzname, self._utcoffset, dst
jpayne@69 515 )
jpayne@69 516 else:
jpayne@69 517 return '<DstTzInfo %r %s%s %s>' % (
jpayne@69 518 self.zone, self._tzname, self._utcoffset, dst
jpayne@69 519 )
jpayne@69 520
jpayne@69 521 def __reduce__(self):
jpayne@69 522 # Special pickle to zone remains a singleton and to cope with
jpayne@69 523 # database changes.
jpayne@69 524 return pytz._p, (
jpayne@69 525 self.zone,
jpayne@69 526 _to_seconds(self._utcoffset),
jpayne@69 527 _to_seconds(self._dst),
jpayne@69 528 self._tzname
jpayne@69 529 )
jpayne@69 530
jpayne@69 531
jpayne@69 532 def unpickler(zone, utcoffset=None, dstoffset=None, tzname=None):
jpayne@69 533 """Factory function for unpickling pytz tzinfo instances.
jpayne@69 534
jpayne@69 535 This is shared for both StaticTzInfo and DstTzInfo instances, because
jpayne@69 536 database changes could cause a zones implementation to switch between
jpayne@69 537 these two base classes and we can't break pickles on a pytz version
jpayne@69 538 upgrade.
jpayne@69 539 """
jpayne@69 540 # Raises a KeyError if zone no longer exists, which should never happen
jpayne@69 541 # and would be a bug.
jpayne@69 542 tz = pytz.timezone(zone)
jpayne@69 543
jpayne@69 544 # A StaticTzInfo - just return it
jpayne@69 545 if utcoffset is None:
jpayne@69 546 return tz
jpayne@69 547
jpayne@69 548 # This pickle was created from a DstTzInfo. We need to
jpayne@69 549 # determine which of the list of tzinfo instances for this zone
jpayne@69 550 # to use in order to restore the state of any datetime instances using
jpayne@69 551 # it correctly.
jpayne@69 552 utcoffset = memorized_timedelta(utcoffset)
jpayne@69 553 dstoffset = memorized_timedelta(dstoffset)
jpayne@69 554 try:
jpayne@69 555 return tz._tzinfos[(utcoffset, dstoffset, tzname)]
jpayne@69 556 except KeyError:
jpayne@69 557 # The particular state requested in this timezone no longer exists.
jpayne@69 558 # This indicates a corrupt pickle, or the timezone database has been
jpayne@69 559 # corrected violently enough to make this particular
jpayne@69 560 # (utcoffset,dstoffset) no longer exist in the zone, or the
jpayne@69 561 # abbreviation has been changed.
jpayne@69 562 pass
jpayne@69 563
jpayne@69 564 # See if we can find an entry differing only by tzname. Abbreviations
jpayne@69 565 # get changed from the initial guess by the database maintainers to
jpayne@69 566 # match reality when this information is discovered.
jpayne@69 567 for localized_tz in tz._tzinfos.values():
jpayne@69 568 if (localized_tz._utcoffset == utcoffset and
jpayne@69 569 localized_tz._dst == dstoffset):
jpayne@69 570 return localized_tz
jpayne@69 571
jpayne@69 572 # This (utcoffset, dstoffset) information has been removed from the
jpayne@69 573 # zone. Add it back. This might occur when the database maintainers have
jpayne@69 574 # corrected incorrect information. datetime instances using this
jpayne@69 575 # incorrect information will continue to do so, exactly as they were
jpayne@69 576 # before being pickled. This is purely an overly paranoid safety net - I
jpayne@69 577 # doubt this will ever been needed in real life.
jpayne@69 578 inf = (utcoffset, dstoffset, tzname)
jpayne@69 579 tz._tzinfos[inf] = tz.__class__(inf, tz._tzinfos)
jpayne@69 580 return tz._tzinfos[inf]